No they are not. Taxis aren't public transport either.
This CityAirbus takes what, 4-6 people seated? A bus easily takes 40+, a tram 60+ and a metro 250+* - and that's just seats, they all fit hundreds of people if you include standing passengers.
It would take ages and hundreds/thousands of flying taxis to clear a stadium, while it takes only tens of metro trains.
* Numbers taken from public transport options in my home town, will of course differ around the world